Agriculture is the largest economic sector in the world. The awareness of the current environmental degradation caused by conventional farming practices has allowed the use of entomopathogenic fungi as a biological control technique to become increasingly widespread. Several studies from the laboratory bench to field trials show that fungi can be directly applied or, more recently, can be carried to the target by other biological vectors (i.e., insects), which increases their potential for dispersal and transmission. In addition, studies on the development of formulations have intensified, with the aim to enable their commercialization and reduce costs for the more sustainable management of crops. This review discusses the positive aspects of the use of filamentous fungi in the biological control of pests, specifically in terms of the use of antagonistic fungal plant pathogens and nematophagous fungi.

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Filamentous fungi in biological control: current status and future perspectives

Incorporating beneficial microorganisms in crop production is the most promising strategy for maintaining agricultural productivity and reducing the use of inorganic fertilizers, herbicides, and pesticides. Numerous microorganisms have been described in the literature as biological control agents for pests and diseases, although some have not yet been commercialised due to their lack of viability or efficacy in different crops. Paecilomyces is a cosmopolitan fungus that is mainly known for its nematophagous capacity, but it has also been reported as an insect parasite and biological control agent of several fungi and phytopathogenic bacteria through different mechanisms of action. In addition, species of this genus have recently been described as biostimulants of plant growth and crop yield. This review includes all the information on the genus Paecilomyces as a biological control agent for pests and diseases. Its growth rate and high spore production rate in numerous substrates ensures the production of viable, affordable, and efficient commercial formulations for agricultural use.

https://www.mdpi.com/2223-7747/9/12/1746/pdf

Paecilomyces and Its Importance in the Biological Control of Agricultural Pests and Diseases

In the present study, P. variotii, an endophytic fungus isolated from plant roots from the Cabo de Gata Natural Park (Parque Nacional Cabo de Gata—Spain), was tested to determine the effect on the growth promotion of tomato and pepper seeds and seedlings. For these purposes, germination trials in a laboratory and two experiments in a commercial nursery and greenhouse conditions were performed. The P. variotii isolate has shown a high ability to produce siderophores and IAA, but low ability to solubilize P. High values for germination percentage, seedling vigor, root and shoot length were obtained by P. variotii on tomato and pepper against control. P. variotii applications resulted in improved most of the growth parameters evaluated, for both horticultural crops, with the best results in the development of pepper seedlings. The application of a higher dose of P. variotii improved most of the morphological parameters and the Dickson quality index (DQI) value in tomato in seedlings and plants. The establishment of the endophytic fungus at the root enabled its biostimulant effects to persist after transplantation without any additional application. Few studies have analyzed this species as a biostimulant. The positive results from the tests showed its high potential. The application of this isolate can be of enormous benefit to horticultural crops for its high reproductive and establishment capacity.

Paecilomyces variotii as A Plant-Growth Promoter in Horticulture

The main objective of this study was to determine the capacity of Trichoderma aggressivum f. europaeum to promote pepper and tomato seedling growth compared to that of T. saturnisporum, a species recently characterised as a biostimulant. Consequently, in vitro seed germination and seedling growth tests were performed under commercial plant nursery conditions. Additionally, the effects of different doses and a mixture of both species on seedling growth under plant nursery and subsequently under greenhouse conditions were determined. Furthermore, mass production of spores was determined in different substrates, and their siderophore and indole acetic acid production and phosphate (P) solubilisation capacity were also determined. Direct application of Trichoderma aggressivum f. europaeum to seeds in vitro neither increases the percentage of pepper and tomato seed germination nor improves their vigour index. However, substrate irrigation using different doses under commercial plant nursery conditions increases the quality of tomato and pepper seedlings. Tomato roots increased by 66.66% at doses of 106 spores per plant. Applying T. aggressivum f. europaeum or T. saturnisporum under plant nursery conditions added value to seedlings because their growth-promoting effect is maintained under greenhouse conditions up to three months after transplantation. The combined application of the two species had no beneficial effect in relation to that of the control. The present study demonstrates the biostimulant capacity of T. aggressivum f. europaeum in pepper and tomato plants under commercial plant nursery and greenhouse conditions.

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Role of Trichoderma aggressivum f. europaeum as Plant-Growth Promoter in Horticulture

Liquid bioformulations for the management of root-knot nematode, Meloidogyne hapla that infects carrot

We evaluated the nematicidal potential and phosphate solubilization ability of the fungal species Geomyces pannorum and Paecilomyces carneus, which are associated with the potato cyst nematode Globodera rostochiensis. In a broth medium containing calcium phosphate, the two fungi solubilized between 67%-96% of the insoluble phosphorus that was present in the medium, and in a broth medium containing iron phosphate, the phosphorus that was solubilized by the two fungi ranged between 2%-13%. In a greenhouse experiment, G. pannorum and P. carneus were applied to soil that was naturally infested with G. rostochiensis and planted with Avena sativa. The fungi increased the available phosphorus in the soil by more than 30%, and Paecilomyces carneus also reduced the nematode population by 71%. This study is the first to report on the ability of G. pannorum and P. carneus to increase the available phosphorus in the soil, suggesting that these fungal species may have potential uses in agricultural soils with insoluble phosphorus. Moreover, this study provides a new alternative that contributes to the sustainable management of crops with bio-agents that have dual activity; they increase the available phosphorus in the soil and mitigate plant parasitic nematodes.

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D. L Lima-Rivera

Papers

Phosphate solubilization by fungi with nematicidal potential